One on my patients, a 13-year-old boy, has right +0.50 DS and left -9.00 DS. He does not wear glasses nor contact lenses. His mother has asked if there is anything that can be done to help him see better with his left eye. He was examined in an eye hospital when he was 7 years old and was told it was too late to do anything to improve the vision in his left eye. His right visual acuity is 6/5 and left with full refractive correction 6/60. He does not have any significant strabismus. What can I do?
This is a case of anisometropia. Glasses will not be a solution to this since the difference in retinal image size will be too great for the visual system to cope with. The right plus spectacle lens will cause a slight magnification of the retinal image while the left minus lens will cause a lot of minification. This difference in image size could lead to double vision and/or headaches and eye aches.
One option to try is a silicon hydrogel daily disposable contact lens for the left eye only. All the brands I am familiar with come in a -9.00 DS power and with the modern material and no cleaning solutions required this makes sense for a teenager in terms of hours of wear and hygiene.
In terms of benefit to the left eye visual acuity it is possible that during the years when visual development takes place, from birth to around 7 years old, the myopia may have been less than -9.00 DS allowing some distance visual stimulation-even if blurry-and definitely some less blurry near visual stimulation. There may be some latent visual acuity that can be salvaged and the amblyopia may not be as bad as seems at first look.
I remember working on a similar case where the patient was 10 years old, had plano in one eye, -6.00 DS in the other and no glasses or contact lenses. The myopic eye had a visual acuity of 6/60 when corrected in the practice but this improved to 6/12 after three months of contact lens wear. The parents were delighted.
I suggest trying a contact lens for the left eye with review in two weeks to how things are going and then another review in two weeks to monitor the left visual acuity although this may not improve for two to three months. If there is no improvement after this period then contact lens wear can be stopped and advice given on eye protection from trauma to the right eye.